Various means have been used in the prior art to improve the performance of a projectile's lethality. Improvements in projectile lethality against armored vehicles and reinforced positions have been accomplished in some instances by use of a sabot which increases the projectile's velocity, accuracy and range. This improvement occurs in a sabot supported projectile because the bore area on which the gun pressure acts may be greatly increased with only a relatively small increase in total projectile weight. In addition there is improvement because the use of a small diameter flight body has less aerodynamic drag. To obtain optimum performance a sabot mass must be kept as low as possible while remaining within the constraints set by the structural requirements of the sabots.
Some of the problems with prior art discarding sabot designs have been related to increased propellant gas pressure and acceleration. The gas pressure and accelerating forces acting on prior art sabots usually generate stress fields with hoop or circumferential tension components. These stresses frequently cause splits between the sabot segments which prematurely vent the propellant gas. In prior art designs in order to prevent this leakage of gas, the gun tube was required to provide constraint until the opening of the sabot, and an additional structural seal was required to those areas exposed to the propellant gas pressure.
In sabot propelled projectiles, the propellant force acting on the surface of the sabot, is applied toward the acceleration of the subprojectile at the interface of the sabot and the subprojectile. The configuration of prior art sabots generally is such that this shear traction is very nonuniform along the axial dimension of the interface. This nonuniform shear traction is a very severe disadvantage in obtaining maximum load transfer in a fixed dimension device such as the bore diameter of a launch weapon.
Another problem with prior art sabot designs, especially prevelant in submunitions with large length to diameter ratios, is the in-bore and out-of-bore dynamic instability which causes the projectile to yaw. In the prior art, the rotating band or obturating band is generally located aft of the center of gravity of the full in-bore projectile. To counteract the high transverse loads generated by this inherent instability, additional boreriding support required for straightening and guidance must be made excessively rigid and heavy.